3.4 Effects of different substrates on rhizosphere microbial communities
The dominant bacterial species of each group were similar (Fig.5). At the phylum level, Proteobacteria and Chloroflexi were the top two dominant bacteria in all samples, and Proteobacteriaaccounted for 16.94%-21.55%, and Chloroflexi accounted for 14.82%-22.48%. However, the influences of different substrates on the proportion and composition of dominant bacteria were different. No difference in the relative abundance of Chloroflexi among ME, VE, or VR groups, but it was lower in these three treatment groups than in CK group, whereas the relative abundance of Chloroflexi in the CE group was higher than that in CK group. Additionally, the relative abundance ofDesulfobacterota and Nitrospirota in 4 treatment groups was higher than that in CK, while the relative abundance ofAcidobacteriota was the opposite.
On day 40, Ace, Chao, Sobs, and Shannon indexes in all 4 treatment groups were higher than CK (Table S1), among which group VE was the highest, followed by group VR. The ME, VE, and VR groups exhibited a lower Simpson index than CK group, while CE group displayed a higher one than CK. These results indicated that the substrate addition could increase diversity and abundance of rhizosphere microorganisms.